Choice of equipment

Up to now it was assumed that reaction and distillation can favourably be combined in a column - in a normal distillation coluitui in the case of homogeneous catalysis, and in a column with special internals or an additional exterior volume in the case of heterogeneous catalysis. This was discussed in the previous chapter under the aspect of scale-up in connection with separation and reaction performance. However, columns are an appropriate solution only for reactions that are so fast as to achieve considerable conversions in the residence time range of such columns. The question is whether the full potential for comhining reaction and distillation can be found and industrially implemented using columns only. 

Industrial process design should aim at operating conditions within these two ranges just the sufficient residence time and only the necessary expenditure for the distillation. 

So we have a second scale-up problem what is the suitable equipment for complying with these demands This means more precisely how can the reactor performance be achieved over a broad range of reaction velocities Different equipment may be chosen to combine reaction and distillation within the limiting conditions of reaction velocity, relative volatility and catalysis. 

The next considerations concentrate on homogeneous catalysis. Similar considerations apply to heterogeneous catalysis, and this will be commented on later. 

At first, a slow reaction is considered. Slow means that the reaction rate is slow, compared with the residence times typical for separation equipment such as distillation trays. For residence time reasons a stirred vessel or, better, a cascade of stirred vessels is needed. Each vessel is supplied with energy to evaporate the component to be separated. If the relative volatility of this component is very high, a one-stage evaporation is sufficient. At a lower relative volatility, the separation 

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The combustible components of the gas are carbon monoxide and hydrogen, but combustion (heat) value varies because of dilution with carbon dioxide and with nitrogen. The gas has a low flame temperature unless the combustion air is strongly preheated. Its use has been limited essentially to steel (qv) mills, where it is produced as a by-product of blast furnaces. A common choice of equipment for the smaller gas producers is the WeUman-Galusha unit because of its long history of successful operation (21). 

Environmental Protection. Fumes resulting from exposure of anhydrous aluminum chloride to moisture are corrosive and acidic. Collection systems should be provided to conduct aluminum chloride dusts or gases to a scmbbing device. The choice of equipment, usually one of economics, ranges from simple packed-tower scmbbers to sophisticated high energy devices such as those of a Venturi design (11). 

Specific Surface. If a defined specific surface area is required, this can affect the choice of equipment. Machines that apply stress by cmshing generally create more ultrafines, and hence higher surface area, than impact mills. 

The formulation of a carrier depends on four considerations (/) the carrier-active chemical compound (2) the emulsifier (J) special additives and (4) environmental concerns. Additional parameters to be considered in the formulation of a carrier product with satisfactory and repeatable performance arise from the equipment in which the dyeing operation is to be carried out. The choice of equipment is usually dictated by the form in which the fiber substrate is to be processed, eg, loose fiber, staple, continuous or texturized filament, woven or knot fabric, yam on packages or in skeins (see Textiles). 

Clearly, these groupings are not mutually exclusive. The chief distinctions are between homogeneous and heterogeneous reactions and between batch and flow reactions. These distinctions most influence the choice of equipment, operating conditions, and methods of design. 

Choice of equipment based on first cost only will almost certainly result in an undersized condenser and a high head pressure. 

In the past, a processor desiring to enter the field had little choice of equipment, but the increased interest in coextrusion has produced a proliferation of equipment. With rapidly changing market conditions and the endless... 

The choice of equipment will also depend on whether the prime objective is to obtain a clear liquid or a solid product, and on the degree of dryness of the solid required. 

Making Incorrect Assembly Impossible -choice of equipment, piping and fittings correctly equipment safety safe process structure... 

Other, more specific decisions are made in process design, including the actual choice of equipment (e.g., more than ten different types of heat exchangers are available) and the selection of construction materials of various process units. 

You have four choices of equipment (as shown in the following table) to solve a pollution control problem. The choices are mutually exclusive and you must pick one. Assuming a useful life of 10 years for each design, no market value, and a pretax minimum acceptable rate of return (MARR) of 15% per year, rank them and recommend a choice. 

The size range of commercial aerosols and the methods available for determination of particle size and for removing the particles from the gas are shown in Figure 1.50, which is taken from the work of Ashman. It may noted that the ranges over which the various items of equipment operate overlap to some extent, and the choice of equipment depends... 

Too many chromatographic texts dwell heavily on a theoretical and mathematical complexity that bears little relevance to what you actually need to do in order to practice preparative HPLC. Hopefully this book will describe how to practically go about a preparative separation. It is designed to guide the reader through the choice of equipment and chromatographic modes with minimal fuss and with reference to only relevant formulae. Much of the black art will be removed by the hints and tips of a practitioner with over 20 year s experience in many modes of chromatographic separation. 

Citric acid and vitamin C are examples of very large scale fermentation processes where the subsequent product isolation involves several bioseparations, including filtration, precipitation, evaporation, crystallization, and drying methods. The scale of operation requires careful choice of equipment which is robust, efficient in separating product from unwanted by-products, and cost effective to be competitive. 

In the industries using bioseparations described above, there is a great variation in terms of production scale and product quality between waste water treatment and pharmaceutical production. This will obviously affect the choice of equipment for the process, although in many cases the principle on which bioseparation is based will be common. For example, centrifuga-... 

We illustrate the choice of equipment with the example of Wokkels in Figure 13-2. Nowadays this product is nothing special you can find something like it in any supermarket. However, 30 years ago, this was a big hit for its developers. Try to think of yourself in their... 

This lesson has introduced you to the choice of equipment for the plant. 

Given the choice of equipment today and its cost relative to conventional solvent based cleaning, (see Ch. 10 by Huse and Smith), the advantages of SCF cleaning make it very attractive compared to aqueous or organic based systems. Capabilities of solvent tunability... 

Choice of equipment for the processing line is very important for the production of margarines. For each piece of equipment in the production line, special design features have to be considered for various margarine types to ensure that the complete processing line has all the necessary capabilities. 

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